The present invention relates to a knee orthosis preventing hyperextension, i.e. excessive extension of the knee joint. The orthosis features a two-axes joint allowing a natural joint motion and a popliteal connection bar providing the required stability. The orthosis is light-weight and made of few components. The orthosis allows easy donning and doffing by incorporating adequate straps.
The first version of the hyperextension orthosis consisted of a rigid brace without any hinge of joint. Thus, it did not bend with the leg which, of course, was impractical. This orthosis was replaced by an orthosis having a single axis joint. Even though this was an improvement over the rigid brace, the single axis joint did not follow the natural motion of the knee joint. The orthosis was provided with a stabilizing connection bar in the popliteal space. When the patient bent the knee joint, the leg pinched around the connection bar. Thus, the movement of the patient""s leg was limited and experienced as uncomfortable. Furthermore, the orthosis was secured to the leg by ventral and dorsal straps attached to the orthosis at the same height. Due to this arrangement, the orthosis was subject to slipping down the leg.
The present invention solves the problems stated above by providing a knee orthosis comprising a two-axes joint promoting a natural motion. Also, the ventral and dorsal straps are arranged at different heights and preferably offset from a centre line. This arrangement distributes the forces and torques on the orthosis in an advantageous manner preventing slipping.
Thus, the present invention provides a knee orthosis comprising a top portion to be secured at the patient""s thigh and a lower portion to be secured at the patient""s lower leg, a joint portion connecting the top and lower portions, and strap means for securing the orthosis. According to the invention the joint portion has two axes preventing hyperextension but otherwise allowing a free motion of the patient""s leg.
Preferably, the joint portion comprises two hinges connected together by a connection bar positioned in or near the popliteal space.
In a preferred embodiment, the top and lower portions comprise brace members having ventral and dorsal slits for the strap means. The ventral and dorsal slits are positioned at different heights and may be offset from the centre line of the orthosis.
The invention is set forth in greater detail in the accompanying claims.